Saturday, March 11, 2006

It’s a dog-eat-dog world

From Michigan comes this report of wolves attacking one another on Isle Royale National Park. Seems the moose population levels have declined to the lowest levels in 48 years. With few of their usual prey species around the wolves invade other pack’s territory and hunt the hunters. Actually, the wolves don’t see one another as a food source. No, they see one another as competitors. One of the three packs has already lost its alpha male and may be on the verge of dispersing.

Moose have become unavailable due to an aging population.
The population decline results in part from the aging of a "baby boom" generation dating from the early 1990s, when wolf numbers plummeted because of a parvovirus outbreak, he said. Also, a tick infestation in recent years weakened the animals, making them easy prey for wolves.
Wolves find the elderly and calves more easily attacked. Right now, the bulk of the moose population ins in its prime and pretty much off limits to the wolf packs. They’ve already eaten the old and are working on the calves.
"One-third of the kills this winter were calves," Peterson said. "The wolves need to go down to give more calves a chance of reaching adulthood."

The closed ecosystem of Isle Royale has produced another problem:
The tick problem eased during the past year but remains a threat. Another is a gradual decline of the moose's primary food supply as the island's forests evolve from primarily birch and aspen to less nutritious spruce and balsam fir, Vucetich said.

The changing forest cover has caused a sharp drop in beaver, an alternative food source for wolves, Peterson said.

So, let’s summarize.
1-In the ‘90s, parvovirus and ticks weakened the wolves. Fewer wolves meant more moose calves surviving.
2-More moose calves meant the wolves would remove the elderly from the population as a lone old moose would be easier prey than a calf with an angry mother.
3-Wolf numbers increased along with the teenage moose population.
4-Large numbers of moose (and time) brought about a change in the forest of Isle Royale with the moose’s preferred foods, aspen and birch being replaced by spruce and balsam fir. 5-Declining nutritious foods means weaker old moose—pfft they’re gone. (The change over also means fewer beaver—a secondary food source for the wolves.)
6-No elderly moose means the wolves have to eat calves and that means fewer moose which means fewer wolves can survive.


And this is for just a few species wolves, moose, beaver, aspen, birch, spruce and balsam fir. No mention of the birds affected by the plant change, the insects, other trees and shrubs, any herbaceous plants…. Aw, you get the idea. Next time an environmentalist or wildlife biologist tells you he knows what’s happening…take it with a grain of salt. The variables are tremendous. And predictions are written on tissue paper.

Via Yahoo! News

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